Apparatus for expanding metals with curved surfaces such as pistons



"lavlw a; i.

Fi'led Feb. 13, 1956 P. CHARLTON 2,945,405 APPARATUS FOR EXPANDING METALS WITH CURVED SURFACES SUCH AS PISTONS July 19, 1960 7 Sheets-Sheet 1 Inventor V E Chamlwzv P. CHARLTON July 19,1960 APPARATUS FOR EXPANDING METALS WITH CURVED SURFACES SUCH AS PISTONS 7 Sheets-Sheet 2 Filed Feb. 15, 1956 Inventor Charlton Attorneys July 19-1960 P. CHARLTON APPARATUS FOR EXPANDING METALS WITH CURVED SURFACES SUCH 1S PISTONS 7 Sheets-Sheet 3 m Feb. 1:, 195 s.

1 n venlor A ttorn e July 19, 1960 P. CHARLTON APPARATUS FOR EXPANDING METALS WITH CURVED SURFACES SUCH AS PISTONS 7 Sheets-Sheet 4 Filed Feb. 13. 1956 Inventor A ttorneys zAPfARATUS FOR EXPANDING METALS WITH CURVED SURFACES SUCH AS PISTONS lsss r '7 Shee ts-Sneat 5 a LO Inventor emv P. CHARLTON APPARATUS FOR EXPANDING METALS WITH CURVED SURFACES SUCH As PISTONS July 19, 1960 7 Sheets-Sheet 6 Filed Feb. 13, 1956 July 1960 P. CHARLTON 2,945,405

APPARATUS FOR EXPANDING METALS WITH CURVED SURFACES SUCH AS PISTONS 7 Sheets-Sheet 7 Filed Feb. 13, 1956 lnvenlor United States ateint APP RATUS FOR EXPANDING METALS WITH cuRvEn SURFACES SUCH AS PISTONS ihilip Charlton, Kelbum, Wellington, New Zealand, as-

szignlor to Motor Specialties Limited, Auckland, New

ea and Filed Feb. 13, 1956, Ser. No. 565,240

Claims priority, application New Zealand Feb. 22, 1955 '7 Claims. (Cl. 78-131) This invention relates to an apparatus for expanding metals and more particularly relates to the expansion of metal shapes or articles which have curved surfaces, such as pistons.

It is an object of the invention to provide an apparatus for expanding curvilinear form metal by placing a convex surface of the metal to be expanded in juxtaposition to .a convex anvil, striking the concave surface of the metal remote from and opposite to its line of contact with the convex anvil with a hammer to form a depression in the concave surface and cause the metal to flow to produce a raised edge projecting from such concave surface on each side of the depression in the metal and, while holding the metal against the convex anvil by said hammer, subjecting each raised edge projecting from the concave surface to the depressing effect of additional hammers to expand the metal of the raised edges laterally away from the initial depression.

Further according to the invention the apparatus for expanding metal or metal articles having opposite convex and concave surfaces comprises an anvil having a convex striking surface adapted to support and back up the convex surface of the metal to be expanded, an initial hammer, means constructed, arranged and operable to move said hammer to strike the concave surface of the metal while it is bearing against or resting on the convex surface of the anvil to form an initial depression in the concave surface and cause the metal to flow to provide a raised edge projecting'from the concave surface on each side of the depression in the metal, means holding the initial hammer into or maintained against the metal to hold it against the convex surface of the anvil, flanking hammers, and means operable to move said flanking hammers to strike the metal of each raised edge or rim on the sides of the depression to depress and to expand the metal of the raised edges away from the initial depression.

The apparatus for carrying out the invention will now be further described with reference to the accompanying drawings, in which:

Figure 1 depicts, diagrammatically, the placing of a piston in juxtaposition to an anvil,

Figure 2 depicts, diagrammatically, the operation of the initial, middle hammer striking the concave or inner surface of the piston and the resulting depression,

Figure 3 depicts, diagrammatically, the subsequent operation of the flanking hammers with the initial middle hammer maintained in contact with the depression,

Figure 4 is a side elevation of an apparatus for carrying out the invention, I

Figure 5 is a plan view of the apparatus shown in Figure 4,

Figure 6 is an opposite side elevation of the apparatus shown in Figure 4,

Figure 7 is a front end elevation of such apparatus,

- Figure 8 is a rear end elevation of the machine as seen from the end opposite to that shown in Figure 7,

Figure 9 is a fragmentary elevational view of the "ice apparatus illustrating only the hammers and the operatingmechanism therefore as shown in Figs. 4, 5, 6 and 7,

Figure 10 is a plan view of the components shown in Figure 9,

Figure 11 is an enlarged front end view of the hammers,

Figure 12 is a fragmentary end view partly in eleva tion and partly in cross section of the. hammers and force applying means therefor,

Figure 13 is a plan view of the base of the apparatus, Figure 14 is a side elevation of the base as shown in Figure 13, and

Figure 15 is an end View of the base shown in Figure 14 as viewed from the right.

The operation of the apparatus of this invention is diagrammatically depicted in Figures 1 to 3. In Figure 1 there is shown the first step in the operation wherein a concavo-convex metal element such as a piston is sup ported with its convex face in contact with the convex surface of an anvil and the central arrow A represents the direction of movement of the initial hammer 31a which in Figure 2 has struck the concave surface C0 of the metal such as a piston. In Figure 2 the initial strik ing of the concave surface by the hammer 31a has formed an initial depression D while causing the metal to flow to form a raised edge projecting from the line of the concave surface, thus a raised rim surrounds the initial concave depression, the striking face of hammer 31 being convex, and the metal is pushed and spread in the general direction of the arrows S shown on the piston. Then, as shown in Figure 3, the raised edges or rim of the initial depression is subjected to the depressing effect of blows from the flanking hammers 31b forced down immediately alongside the initial hammer so that the striking faces of the flanking hammers 3l1b hit the edges or rim of the initial depression to expand or forcev i More particularly the rotary anvil 2 is in the form of a rotatable cylinder supported lengthwise of the base plate 1 between the pair of angled bracket supports 3 (see Figs. 4, 5 and 6).

As previously mentioned the invention is concerned chiefly with expanding the walls or skirts of pistons, and in this connection it is essential that the piston be correctly positioned and held on the rotary anvil 2'while it is subjected to the expanding of metal in accordance with this invention. This positioning is efiected by a holding means in the form of adjustable and centering caliper arms, as indicated generally by arrow 4, and

which arms are mounted or supported at the front end of the base plate 1. g

As shown in Figures 4, 5' and 6 each caliper arm 4 includes a vertical or upright section 4* pivotally supported toward the front end of the base plate 1, a horizontal shaft 4 which extends rearwardly from the free end of each vertical section 4 above and in parallel alignment with the rotary anvil 2. The shafts 4 carry grips by which a piston 6 (shown dotted in Figures 4 and 6) is held on the rotary anvil 2, and as illustrated each shaft 4* is provided with rotatable slidable bearings or rolls 4, so that the piston being expanded is grippedbetweeu opposed pairs of grips or bearings 4.

The pivotal support for the caliper arms 4 is mounted to a Plate secured to the front support 3 which supports the rotary anvil 2.

The caliper arms 4 are arranged to be pivoted in unison to a position to suit the size of the piston tobe expanded and further, to hold the piston on the rotary anvil 2 dur ing the subjection of the piston 6 to the operation of metal expansion. To effect such an operation, a vertical guideway 7 is mounted on the front face of plate 5, and within the guideway 7 there is situated a vertical slide base 8 which carries resilient racks. As shown in Figure 7, the resilient racks include upper and lower cross members 811. The chains are forced apart by a compressible resilient means such as rubber grommets or bushings 10 placed between cross members 8 and hearing against the roller chains 9, The slide 8, and the chains 9 are positioned between the lower ends of the caliper arms 4 and the chains are engaged with toothed quadrants 11 secured to or forming part of the caliper arms 4. The rubber grommets 10 are spread apart by a spreading plate 12 hearing onthe outer surfaces of the grommets 10 and secured to slide 8 to ensure that the latter bear against the chains 9 which in turn permit pivotal co-ordinating movement between the arms 4, and further ensure no loss of motion between the arms 4 when the latter are moved toward or away from each other. The chains 9 are therefore, conformable to the toothed quadrants 11 and the lateral shafts 4 of the arms 4 are brought together in desired relative positions ever the rotary anvil 2.

As illustrated in Figure 7 bolts 5 extend forwardly from the plate 5, to provide stops to limit inward movement of each of arms 4. Further, an axiallyv movable stud 5 is mounted for movement through the plate 5 to he slid to a position to project forwardly of the plate 5 in the path of one of the arms 4 to contact such arm and limit the closing movement thereof when it is desired to maintain such arm in an open position.

The bolts 5 when desired, may also, carry a cover plate 5 shown in dotted outline in Figure 7.

The vertical slide 8 is spring influenced (see Figure 7 to draw the slide '8. downwards, whereby chains 9 tend to turn the toothed quadrants 11 to move the arms. 4 in inward co-ordin-ated pivotal movement. For this purpose the lower end of the vertical slide, 8 has one end of a spring 13 anchored thereto, and the opposing end of the spring 13, which is under tension, is anchored to the lower end of a bracket 14 secured to, and. extending below thefront of the base plate 1 (see Figure 7)..

Situated near the rear end, of. the base plate 1 is a horizontal slide 15 in more or less parallel alignment with the axis of the rotary anvil 2. A casting:15 which includes a vertical support-16, is movable on the slide 15 so that thevertical support 16, which supports the. actual peening hammers 31 of the apparatus, may beamoved to or fro m the rotary anvil 2 or longitudinally of the base plate 1 (see Figures 4, 5 and 6).

In this latter connection, such movement. is provided.

through the medium of a crankhandle. 17.. keyed to a transverseshaft 18 turnablein, bearings 19lbolted to the vertical support 16. The. shaft '18 carries a pinion 20 which is engaged with a chain, rack 21 mounted on the upper surface of the base plate 1, (see Figure 5).

Thevertical support 16 has a verticalslideway 22 secured to its rear vertical surface which slidably carries a slidingblock 23, which in turn carries a hammer sup- P9Iling, ,plate means 24 disposed in a vertical position on the slidingblock 23-. The upward movement'of sliding block 23 hasthe effect of raising the peening hammers 31;, Upward and downward movements are imparted to the vertical sliding block 23 by a screwshaft 25 rotatablymountedin a bearing 25%. on, the vertical supp9rt 16, and which screw shaft 25' is in mesh with a threaded nnt 26 secured to the slidingblook 23. Preferably the slideway 22.,is formed by. alpair, of rails as-illustrated in Figure 8. and theworm 25. is carried between 4 the rails to engage the nut 26 which projects through block 23 to be disposed between the rails. The worm 25 is adapted to be turned by means of a crank handle 27 projecting upwardly from the outer edge of a disc 28 secured on the upper end of the worm 25.

As shown in Figure 6 the screw shaft 25 can be braked against turning movement by a spring influenced brake 23 pivotally mounted on pin 29* extending from a side of the vertical support 16, and arranged to be pressed against the undersurface of the disc 28 by a spring 30 to prevent turning of the disc 28 until brake 29 is depressed.

The hammer spindle plate 24 is of angled formation and is secured on the sliding block 23 so that one leg of the plate 24 extends longitudinally of the base plate 1 and towards the rotary anvil 2. The hammer spindle plate 24 serves as a mounting for the. three peening hammers which are indicated generally in the drawings by the arrow 31.

As illustrated in Figures 9 and 11, the peening hammers are in the form of levers and are pivotally mounted on a spindle 32 which projects laterally from the outer surface of the hammer spindle supporting plate 2 4. As shown more particularly in Figure 10, the peening hammers are mounted in side by side relationship on the spindle 32 and they resemble each other in shape. In this latter connection the forward ends of all the hammers are shaped to provide downwardly projecting angled heads 33 which are positioned over the rotary anvil 2, toward the end of the latter adjacent spindle 32.

The hammers 31 are adapted to be raised in pivotal movement against the influence of springs so that when released, they are forced downwardly and strike downwardly under the influence of the springs to hit the corn cave surface of a piston to. expand the metal thereof as it is held on the rotary anvil 2,

To provide such striking force by springs, there is secured to the plate 24 a bifurcated yoke 34 which forms a mounting for three adjustable tension springs 35 (see Figure 12). The bifurcated yoke 34 extends upwardly on either side of the hammers 31 to project above the latter so that the upper end of the yoke 34 can support the upper ends of the tension springs 35. Each spring 35 has its lower end anchored to a hammer at a point rearwardly of the spindle 32. In a preferred arrangement the lower ends of the springs 35 are attached to the hammers with the two outermost springs 35 forwardly of the anchorage of the center spring 35 (see Figure 5). The upper ends of the springs 35 are supported by being attached to a cross pin 36 which is held from turning by engaging in a slot 34 in one side member 34' of the yoke 34. The cross pin 36' is carried by the lower end of a screw bolt 37 which is passed through the upper end of the yoke 34. A knurled nut 38 is screw-threaded on the upper projecting end of the screw bolt 37 and the nut 38 bears against the yoke 34. By rotating the knurled nut 38 to raise or lower the bolt 37 tension is applied to or released from the springs 35. The knurled nut 38 may be locked in set position by a nodule 39' on the nut 38 engaging in a recess on the top of the yoke 34.

Similarly, the hammers are further tensioned by means ofdamper springs 40 attached to each hammer on the underside of the latter and forwardly of the spindle 32. The lower ends of the damper springs 40 are attached to a bracket 41 extending downwardly from the forward end of hammer spindle supporting plate 24. The anchorage of the center damper spring 48 is closer to the hammer supporting spindle 32 than is the mchmtage of the two outer damper springs 40 so that the springs 40;;are separated and do not foul each other while operating.

A guide 43 of bifurcated formation projects from the forward end of the hammer spindle plate 24, and includes sides which guide the forward ends of the hammers 31 during movement of thelatter (see Figure 4).

Asillustrated in Figure 4, a hand operated cam lever 44 is pivotally mounted onit-h'e hammer spindle plate 24,

. the cam lever 44 being adapted to be pivoted for depressing'the rear end portions of the hammers to thus raise the hammer heads 33 to permit metal to be treated to be slid into position on the rotary anvil 2.

A cam spindle 45 is carried in bearings 46 on the rear surface of the hammer spindle supporting plate means 24, and therefore the cam spindle 45 is raised or lowered with the sliding block 23. The cam spindle 45 is power driven through a pulley 45 secured on one end of the cam spindle 45. The opposing end of the cam spindle 45 projects from the bearings 46 in close proximity to the rear ends of the hammers 31 and the projecting end of the cam spindle 45 has a pair of rotatable cam rollers 47. The cam rollers 47 are mounted ofi center in relation to the axis of the cam spindle 45 and are held in position by side plates 48 and bolts 49 fixed to the end of the cam spindle 45. The pair of cam rollers 47 is turned by the cam spindle 45 to engage and then to release the rear end of the hammers 31 to operate the latter by first engaging the rear ends of all the hammers to raise the same, then releasing first the middle hammer 31 and thereafter by releasing the two flanking hammers 31 simultaneously.

In this arrangement, see Figures 9 and 10, the cam rollers 47 are positioned so that during turning movement they will, one at a time, engage and roll along inclined surfaces 50 at the'rear or tail ends of the hammers 31 31 to depress the rear end portions of the latter and thus raise the hammer heads 33 against tension of the springs 35 and 40. Each cam roller 47 then rolls from the ends of the hammers to release the latter and to permit the sudden downward movement of the hammer heads 33 under the influence of the tensioned springs 35 and 40.

The tail ends of the hammers are so formed that the middle hammer 31 is released by the cam rollers 47 immediately before releasing the two flanking hammers 31. Such releasing operation is effected because the tail end of the middle hammer 31 terminates a short distance inwardly of the tail ends of the two flanking hammers 31 Figure 10. Such releasing of the hammers has the effect of causing the middle hammer 31 to initially strike the metal on the rotary anvil 2, such as the skirt of the piston 6, and to form an indentation or depression in the' metal (see-Figures 2 and 3), and while the middle hammer 31 is held in the indentation, the two flanking hammers 31* move down to strike the rim of the indentation made by the middle hammer 31 whereby the metal of the rim is pushed outwardly from the indentation. This effect on the metal is repeated to gain the desired expansion of metal.

A back stop is secured immediately above the tails of the hammers 31. Such back stop can be a bolt 52 held by a nut 53 mounted so that the lower end of the bolt 52 engages with the upper surface of the rear portions of the hammers to limit the upward movement of the rear portions of the hammers. Adjustment of the bolt 52 can be efiected to simultaneously position the rear ends or tails of the hammers relative to the cam rollers.

The rotary anvil 2 has a stop 51 adjacent the rear end thereof and projecting up from bracket 3 to locate the metal such as a piston 6 in relation to the anvil 2 and in relation to the arms 4 which maintain the piston 6 in the desired position on the rotary anvil 2 during operation of the apparatus and treatment of the metal.

As stated above, the hammers comprise the initial or center hammer 31 and the flanking hammers 31 with the latter situated on either side of the initial hammer 31. The hammers are arranged to be operated so that after the operation of the initial hammer 31F, and while the initial hammer 31 is engaged on an article or piece of metal on the curved surface of the convex anvil 2 the flanking hammers 31 are opera-ted simultaneously.

The initial hammer 31 is provided with a rounded ham mer head 33. which may be in the form of a lozenge, so that as the initial hammer head 33 strikes a piece of metal, a depression D is formed in the metal with a raised edge or rim around the depression (see Figures 2 and 3). After its release the initial hammer-31 is driven down by the center springs 35' and 40 to make the depression in the metal, and the hammer 31 is held down under the influence of these central springs 35 and 40 while the flanking hammers 31 are released and are drawn down by springs 35 and 40.

. As illustrated in Figures 2 and 3, the flanking hammers 31 are formed with half rounded or bevelled heads 33' with the curves of the heads 33 facingoutwards and away from the head 33 of the initial hammer 31. Thus the heads 33' of the flanking hammers 31 are situated in juxtaposition to the head of the initial hammer 31 so that the heads of all the hammers operate in conjunction with the convex rotary anvil 2 to expand the metal with the initial hammer 31 making an initial depression with a raised edge or rim projecting up from the concave face or surface of the metal opposite the convex rotary anvil 2. The initial hammer 31 is held within the depression in the metal or article by central springs 35 and 40' while the flanking hammers 31*, with their outwardly curved or bevelled heads 33, strike downward to subject the raised edge or rim on each side of the depression to a blow to expandthe metal away from the initial depression.

As previously stated the hammers are driven by an electric motor (not shown) which can be supported on or adjacent to the apparatus. The electric motor is arranged to rotate the pulley 45 and cam spindle 45 through a belt drive (not shown) to turn the cam rollers 47. The cam rollers 47 in turn bear down on the downwardly inclined upper surfaces 50 of'the tail or rear ends of the hammers to raise the same against the action of springs 35 and '40. Since the cam rollers 47 move down the inclined surfaces 50 and pass ofi' the tail ends of the hammers 31, the springs 35 and 40 cause the hammers to move rapidly downwardly to effect above described blows against the metal. Hence the continual turning of the shaft of the electric motor moves the cam rollers 47 round to intermittently engage thetail ends of the hammers to raise the heads 33 and release the initial or central hammer 31 earlier than the flanking hammer 31', since the initial hammer 31 -is shorter than the flanking hammers 31 The invention will now be described for treating a piston 6 to expand the latter.

The arms 4 are moved apart and the skirt of the piston 6 is inserted under the hammer heads 33 to bear against the anvil back stop 51, so that the piston rests on the rotary anvil 2. Then the arms 4 are allowed to close on to the piston 6 to effect centralization of the piston 6 on the rotary anvil 2. The crank handle 27 is then turned 'to raise or to lower .the sliding block 23 carrying the hammers 31 to position the hammer heads '33 at a selected height in relation to the interior surface of the piston skirt. The crank handle 17 is then turned to move thevertical support 16 longitudinally of the base plate 1 to position the hammer heads 33 in a desired position such as adjacent one of the bosses of the piston, then the piston 6 is turned until the hammer heads 33 are disposed to move downwards to strike the position selected. The hand cam lever 44 is next released and the apparatus set in motion. With the hammers peening it is desirableto direct the hammers 31 in a straight line so that theyoperate towards the top of the piston 6 and adjacent the boss of the piston for several seconds.- Next stopthe ap paratus from operating and turn the piston 6 to its opposite boss and. the surface adjacent the opposite boss is presented to the hammer heads 33. The processisrepeated as before, and while the apparatus is still running the piston 6 is turned in a clockwise direction at the same time hammering the extreme lower edge of the skirt of thepiston 6. until the hammer heads 33 are adjacent The remaining portion of the skirt of the piston 6- is treatedin the same manner as before, and then the piston 6 is further rotated in the same direction (preferably clockwise), and the remaining boss is treated in a similar manner along the edge of the skirt. The handcam lever 44 is then depressed to raise the hammers '31 from the skirt of the piston 6. The caliper arms 4- are opened to release the piston 6 from the rotary anvil 2. The piston 6 is then measured with a micrometer and checked for increase in size. Should any portion of the piston 6-need further expansion, it is returned to the apparatus and treated as before, with a longer period of treatment on the part needing further expansion. This piston his then removed as before and given a final micrometer check.

As used in peening a solid alloy piston 6, the thrust and countersides of the piston 6 are expanded, and peen-. ing of the piston 6 is efiected in the vicinity of the top of the skirt adjacent to the boss, and is continued to the edge or bottom of the skirt while the piston 6 is resting on the convex surface of the anvil 2. Similarly peening of the piston 6 is effected to the other boss of the piston 6 from the top of the skirt or the bottom thereof whereby the counterthrust and thrust sides of the piston 6 are expanded.

In carrying out the method the convex surface of the piston din the vicinity of the area being treated is bearing against the convex surface of the rotary anvil 2. In such arrangement the blows of the hammer 31 during peening are made in the same line as the aligned diameters of the curved anvil 2 and the cylindrical piston 6.

What I do claim and desire to obtain by Letters Patent of the United States of America is:

1. Apparatus for expanding metal shapes of concavoconvex configuration comprising an anvil having a convex shape supporting surface, means adapted to hold a shape to be expanded on said surface with the convex face of the shape engaging said surface along a tangential line of contact, a plurality of reciprocable hammer means adapted to be reciprocated relative to the convex surface of the anvil, said hammer means including a central hammer means having a striking head adapted to produce a depression in the concave face of such a supported shape and to cause metal to flow to form protuberances projecting from the concave face of a supported shape at least on opposite sides of the depression, and flanking hammer means having a striking head means disposed immediately adjacent each side of the head of the central hammer, the shape of the striking head means of the flanking hammer means being such as to be adapted to depress the protuberances to cause the metal to flow laterally away from the depression to expand the shape, means for supporting and positioning the hammer means relative to the anvil to dispose the head of the central hammer means to strike a supported shape opposite said line of contact, and means for reciprocating said central and flanking hammer means, said reciprocating means including means for operating the central hammer means in advance of the flanking hammer means to positively move the head of the central hammer means toward the anvil before said flanking hammers move in the same direction, said last named means being operative to hold the head of the central hammer means in shape engaging position, said reciprocating means thereafter operating the flanking hammer means to positively move the head means thereof toward the anvil so that they are adapted to simultaneously strike such a supported shape on opposite sides of and immediately adjacent the area of such shape struck by said central hammer means.

2. Apparatus for expanding metal shapes of concavoconvex configuration such as pistons, comprising a base, a cylindrical anvil supported on said base, means adapted tohold such a shapeto be. expanded on-the cylindrical anvil with the convex face of the shape engaging the anvil along a line of contact lying in the diametral plane of the anvil, a plurality of reciprocable hammer means adapted to be reciprocated relative to the anvil, said hammer means including acentral hammer means having a striking head shaped so as to be adapted to produce a depression in the concave face of such a supported shape so as to cause metal to flow to form protuberances projecting from the concaveface thereof at least on opposite sidesof the depressiomand flanking hammer means each having a striking head disposed immediately adjacent one side of the striking head of the central hammer'means, the striking heads of the flanking hammer means being shaped so .as to be adapted to depress such protuberances and to cause the metal to flow laterally away from such depression to-expand the shape, means for supporting and positioning the hammer means relative to the anvil to dispose the head of the central hammer means to move toward the anvil in a shape-striking stroke opposite. a line lying in the diametral plane of said anvil, drive means for reciprocating the hammer means, including spring force applying means operatively connected between the hammer means and the. means for supporting and positioning the hammer means to normally urge the hammer means to move in a direction toward the anvil and mechanism for withdrawing the hammer means away from the anvil to tension said spring force applying meansand to sequentially release the central hammer means in advance of the flanking hammer means to cause the head of the central hammer means to initially move toward the anvil to strike the concave face of such a supported shape to form a depression therein and to then release the flanking hammer means to cause the heads thereof to simultaneously move toward the anvil to strike such a supported shape on opposite sides of and immediately adjacent the striking head of the central hammer means.

3. Apparatus as claimed in claim 1 in which said anvil comprises a cylindrical anvil, a base plate, and means supporting said cylindricalanvil for rotation about an axis parallel to the plane of the base plate, the means adapted to hold a shape to be expanded on the anvil comprising a pair of arm means pivotally connected relative to the base plate for movement about axes on each side of the axis of. rotation of the anvil, shape engaging means carried by each arm means and adapted to engage the exterior of a supported shape on the side of its center line remote from the anvil, .means for applying resilientforce to the arm means to hold the shape engaging means in a position to contact the exterior of a supported'shape, and means interconnecting the arm means for simultaneous movement in opposite directions.

4. Apparatus as claimed in claim 3 in which the means for interconnecting the arm means for simultaneous movement in opposite directions include a toothed quadrant fixed to each arm coaxial with the pivoting axis thereof, and movable resilient rack means mounted on the base plate and in mesh with said quadrant and resilient force applying means biased between an anchoring point secured to the base plate and the resilient rack means, to normally urge the rack means to move in a direction to turnthe quadrants to move the arm means to shape engaging position.

5. Apparatus as claimed in claim 1 and including a base plate, said anvil comprising a cylindrical anvil and means carried by the baseplate rotatably supporting the anvil for turning movement about an axis parallel to the base plate, the means adapted to hold a shape on the anvil comprising pivotally mounted shape engaging means secured to'the base plate for pivotal movement about axes laterally displaced from but parallel to the axis of the anvil, rolling-contact shape surfaceengaging means carried by saidarm means and adapted to contact the exterior o fa supported shape on -the side ofthe. center line thereofgremote from-the anvil-and-which center. line 9 extends perpendicular to the direction of movement of said hammer means, and means applying force to the arm means to move the arm means toward one another so that they are adapted to hold a shape in contact with the anvil along said line lying in a diametral plane of the anvil, the means for supporting and positioning the hammer means comprising a support carried by the base plate and means for adjusting the position of the support toward and away from the base plate and longitudinally of the base plate toward and away from the anvil.

6. Apparatus as claimed in claim 1 and including a base plate, the means for supporting and positioning the hammer means relative to the anvil including a support extending generally perpendicular to the base plate, and normally disposed in longitudinal spaced relation relative to the anvil, the hammer means each having an elongated shank having their rear ends terminating in longitudinally spaced relation relative to the anvil, means pivotally securing the hammer means to the support including a spindle passing through the said shanks intermediate the hammer heads and the rear ends of the shanks, spring means operatively connected to the shank to normally bias the hammer heads to move toward the anvil, rotatable cam means carried by the support and engageable with the upper surfaces of the shanks adjacent the rear ends thereof to alternately depress and release the rear ends of the shanks to tension said spring means while withdrawing the hammer heads away from the anvil and to release the rear ends of the shanks so that the spring means forces the hammer heads to move toward the anvil to strike a supported shape and the shank of the central hammer means being shorter than the shanks of the flanking hammer means so that the central hammer means is released from the cam means prior to the release of the flanking hammer means.

7. Apparatus as claimed in claim 1 including a base plate, said anvil comprising a cylindrical anvil and means carried by the base plate for rotatably supporting said anvil for rotation about an axis parallel to the base plate, a slideway extending longitudinally of the base plate, the means for supporting and positioning thehammer means relative to the anvil including a supporting column means extending substantially perpendicular to the base plate and slidably disposed in said slideway for movement toward and away from the anvil, said column means having a slideway therein extending perpendicular to the first-mentioned slideway, a slide means engageable in said second slideway for movement therealong, said slide means including a hammer supporting portion, all said hammer means having substantially the same shape and including elongated shanks, means pivotally connecting the shanks in side by side relationship to the hammer supporting portion for movement about an axis that extends perpendicular to said second slideway, the position of said hammer supporting portion and the pivotal mounting of the hammer means being such that the central hammer means is disposed in a position to have its head overlie the line of contact between a supported shape and said anvil, the shank of the central hammer means being shorter than the shanks of the flanking hammer means, spring means secured in tension between the shanks of the hammer means and the slide means and cam means rotatably mounted on said slide means and operatively related with the upper surface of the rear ends of the shanks to simultaneously depress the rear ends of the shanks to tension the spring means and to release the central hammer means prior to releasing the flanking hammer means due to the difference in length of the shank of the central hammer means.

References Cited in the file of this patent UNITED STATES PATENTS 136,253 Long Feb. 25, 1873 863,477 White Aug. 13, 1907 864,370 Grill Aug. 27, 1907 1,151,005 Gamble Aug. 24, 191-5 1,374,877 Carlson Apr. 12, 1921 1,483,328 Booker Feb. 12, 1924 1,597,268 Diescher Aug. 24, 1926 1,609,785 Steen et al Dec. 7, 1926 1,651,973 Smith Dec. 6, 1927 1,726,731 Bartlett et al. Sept. 3, 1929 1,784,866 Fahrenwald Dec. 16, 1930 1,983,673 Mundt Dec. 11, 1934 2,052,355 Lippard Aug. 25, 1936 2,059,379 Marien et al Nov. 3, 1936 2,172,411 Robertson Sept. 12, 1939 2,194,778 Wiebke Mar. 26, 1940 2,233,913 Colestock Mar. 4, 1941 

